1. Field of Invention
In general, this invention relates to a portable electronic device and more specifically, to a portable electronic navigation analysis device utilizing global positioning system data in calculating estimated time en route and estimated time of arrival.
2. Description of the Related Art
In general, the prior art discloses devices and methods which can calculate a vehicle's estimated time en route and estimated time of arrival. These devices implement a two-part analysis, measuring the vehicle's current velocity and then determining the distance to an established destination. To estimate time en route, some devices divide the distance to the destination by the current vehicle velocity to get an approximate estimated time en route. Additionally, calculating estimated time of arrival entails adding the current time of day to the calculated time en route.
These prior art devices are highly inaccurate for numerous reasons. Often, a vehicle's velocity fluctuates over a given short period. For example, if, at the time the device is sampling the vehicle's velocity, a driver happens to momentarily slow down, the estimated time en route will be inaccurate. Likewise, if the driver is temporarily proceeding at a faster rate than normal, the calculated time en route will be significantly less than the actual time it is likely to take to arrive at the destination.
A second deficiency in current prior art systems is that driving velocities necessarily fluctuate depending on the type of thoroughfare on which a driver is proceeding. For example, on a 4-lane highway, a driver may proceed at 65 mph. However, if the driver exits the highway to a 2-lane road, the average velocity may only be, for example, 25 mph. Therefore, if the sampling of vehicle velocity is done while the driver is on the highway, the calculated time en route will be inaccurate. Likewise, if the sampling of vehicle velocity is done while the driver is on a 2-lane road, the calculated time en route will be much longer than the actual time it is likely to take to arrive at the destination. Moreover, different drivers have different driving habits for different types of thoroughfares.
Finally, based on the equation used by prior art devices to calculate estimated time, if a driver is stopped at the time of sampling vehicle velocity, the velocity of the vehicle will be zero. Because distance is divided by speed, any distance divided by zero will result in an infinite amount of calculated time. Current systems do not account for zero velocity and therefore, the system must reset itself at every point in which a sample velocity is zero. Consequently, all current data is lost and the device must restart the entire process.
Global Positioning Systems (GPS) are well known in the prior art and have a variety of uses. In general, GPS is a satellite-based radio navigation system capable of determining continuous position and velocity information for an unlimited number of users. Formally known as NAVSTAR, the GPS incorporates a plurality of satellites which orbit the earth in extremely precise orbits. Based on these precise orbits, GPS satellites can relay their location to any number of receiving units.
The GPS system is implemented when a device specially equipped to receive GPS data begins scanning radio frequencies for GPS satellite signals. Upon receiving a radio signal from a GPS satellite, the device can determine the precise location of that satellite via one of different conventional methods. The device will continue scanning for signals until it has acquired at least three different satellite signals. Implementing geometrical triangulation, the receiver utilizes the three known positions to determine its own two-dimensional position relative to the satellites. Additionally, acquiring a fourth satellite signal will allow the receiving device to calculate its threedimensional position by the same geometrical calculation. The positioning and velocity data can be updated in real time on a continuous basis by an unlimited number of users.
Based on the above-mentioned deficiencies in the current time calculation devices, there is a need for a navigational analysis device which implements a method utilizing GPS technology that allows for fluctuations in vehicle speed, that can accommodate for the considerations of different types of thoroughfares, and that can sample zero velocity inputs without having to reset the entire system.